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authorLennart Poettering <lennart@poettering.net>2006-06-19 21:53:48 +0000
committerLennart Poettering <lennart@poettering.net>2006-06-19 21:53:48 +0000
commitf44ba092651aa75055e109e04b4164ea92ae7fdc (patch)
tree5dfe076191b32946e78edf64d584d0a65f320013 /src/polyp/stream.h
parentdd21f11deda64e65a6f75817496534c2c9dda1a8 (diff)
big s/polyp/pulse/g
git-svn-id: file:///home/lennart/svn/public/pulseaudio/trunk@1033 fefdeb5f-60dc-0310-8127-8f9354f1896f
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-#ifndef foostreamhfoo
-#define foostreamhfoo
-
-/* $Id$ */
-
-/***
- This file is part of polypaudio.
-
- polypaudio is free software; you can redistribute it and/or modify
- it under the terms of the GNU Lesser General Public License as published
- by the Free Software Foundation; either version 2 of the License,
- or (at your option) any later version.
-
- polypaudio is distributed in the hope that it will be useful, but
- WITHOUT ANY WARRANTY; without even the implied warranty of
- MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU
- General Public License for more details.
-
- You should have received a copy of the GNU Lesser General Public License
- along with polypaudio; if not, write to the Free Software
- Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307
- USA.
-***/
-
-#include <sys/types.h>
-
-#include <polyp/sample.h>
-#include <polyp/channelmap.h>
-#include <polyp/volume.h>
-#include <polyp/def.h>
-#include <polyp/cdecl.h>
-#include <polyp/operation.h>
-
-/** \page streams Audio Streams
- *
- * \section overv_sec Overview
- *
- * Audio streams form the central functionality of the sound server. Data is
- * routed, converted and mixed from several sources before it is passed along
- * to a final output. Currently, there are three forms of audio streams:
- *
- * \li Playback streams - Data flows from the client to the server.
- * \li Record streams - Data flows from the server to the client.
- * \li Upload streams - Similar to playback streams, but the data is stored in
- * the sample cache. See \ref scache for more information
- * about controlling the sample cache.
- *
- * \section create_sec Creating
- *
- * To access a stream, a pa_stream object must be created using
- * pa_stream_new(). At this point the audio sample format and mapping of
- * channels must be specified. See \ref sample and \ref channelmap for more
- * information about those structures.
- *
- * This first step will only create a client-side object, representing the
- * stream. To use the stream, a server-side object must be created and
- * associated with the local object. Depending on which type of stream is
- * desired, a different function is needed:
- *
- * \li Playback stream - pa_stream_connect_playback()
- * \li Record stream - pa_stream_connect_record()
- * \li Upload stream - pa_stream_connect_upload() (see \ref scache)
- *
- * Similar to how connections are done in contexts, connecting a stream will
- * not generate a pa_operation object. Also like contexts, the application
- * should register a state change callback, using
- * pa_stream_set_state_callback(), and wait for the stream to enter an active
- * state.
- *
- * \subsection bufattr_subsec Buffer Attributes
- *
- * Playback and record streams always have a server side buffer as
- * part of the data flow. The size of this buffer strikes a
- * compromise between low latency and sensitivity for buffer
- * overflows/underruns.
- *
- * The buffer metrics may be controlled by the application. They are
- * described with a pa_buffer_attr structure which contains a number
- * of fields:
- *
- * \li maxlength - The absolute maximum number of bytes that can be stored in
- * the buffer. If this value is exceeded then data will be
- * lost.
- * \li tlength - The target length of a playback buffer. The server will only
- * send requests for more data as long as the buffer has less
- * than this number of bytes of data.
- * \li prebuf - Number of bytes that need to be in the buffer before
- * playback will commence. Start of playback can be forced using
- * pa_stream_trigger() even though the prebuffer size hasn't been
- * reached. If a buffer underrun occurs, this prebuffering will be
- * again enabled. If the playback shall never stop in case of a buffer
- * underrun, this value should be set to 0. In that case the read
- * index of the output buffer overtakes the write index, and hence the
- * fill level of the buffer is negative.
- * \li minreq - Minimum free number of the bytes in the playback buffer before
- * the server will request more data.
- * \li fragsize - Maximum number of bytes that the server will push in one
- * chunk for record streams.
- *
- * The server side playback buffers are indexed by a write and a read
- * index. The application writes to the write index and the sound
- * device reads from the read index. The read index is increased
- * monotonically, while the write index may be freely controlled by
- * the application. Substracting the read index from the write index
- * will give you the current fill level of the buffer. The read/write
- * indexes are 64bit values and measured in bytes, they will never
- * wrap. The current read/write index may be queried using
- * pa_stream_get_timing_info() (see below for more information). In
- * case of a buffer underrun the read index is equal or larger than
- * the write index. Unless the prebuf value is 0, Polypaudio will
- * temporarily pause playback in such a case, and wait until the
- * buffer is filled up to prebuf bytes again. If prebuf is 0, the
- * read index may be larger than the write index, in which case
- * silence is played. If the application writes data to indexes lower
- * than the read index, the data is immediately lost.
- *
- * \section transfer_sec Transferring Data
- *
- * Once the stream is up, data can start flowing between the client and the
- * server. Two different access models can be used to transfer the data:
- *
- * \li Asynchronous - The application register a callback using
- * pa_stream_set_write_callback() and
- * pa_stream_set_read_callback() to receive notifications
- * that data can either be written or read.
- * \li Polled - Query the library for available data/space using
- * pa_stream_writable_size() and pa_stream_readable_size() and
- * transfer data as needed. The sizes are stored locally, in the
- * client end, so there is no delay when reading them.
- *
- * It is also possible to mix the two models freely.
- *
- * Once there is data/space available, it can be transferred using either
- * pa_stream_write() for playback, or pa_stream_peek() / pa_stream_drop() for
- * record. Make sure you do not overflow the playback buffers as data will be
- * dropped.
- *
- * \section bufctl_sec Buffer Control
- *
- * The transfer buffers can be controlled through a number of operations:
- *
- * \li pa_stream_cork() - Start or stop the playback or recording.
- * \li pa_stream_trigger() - Start playback immediatly and do not wait for
- * the buffer to fill up to the set trigger level.
- * \li pa_stream_prebuf() - Reenable the playback trigger level.
- * \li pa_stream_drain() - Wait for the playback buffer to go empty. Will
- * return a pa_operation object that will indicate when
- * the buffer is completely drained.
- * \li pa_stream_flush() - Drop all data from the playback buffer and do not
- * wait for it to finish playing.
- *
- * \section seek_modes Seeking in the Playback Buffer
- *
- * A client application may freely seek in the playback buffer. To
- * accomplish that the pa_stream_write() function takes a seek mode
- * and an offset argument. The seek mode is one of:
- *
- * \li PA_SEEK_RELATIVE - seek relative to the current write index
- * \li PA_SEEK_ABSOLUTE - seek relative to the beginning of the playback buffer, (i.e. the first that was ever played in the stream)
- * \li PA_SEEK_RELATIVE_ON_READ - seek relative to the current read index. Use this to write data to the output buffer that should be played as soon as possible
- * \li PA_SEEK_RELATIVE_END - seek relative to the last byte ever written.
- *
- * If an application just wants to append some data to the output
- * buffer, PA_SEEK_RELATIVE and an offset of 0 should be used.
- *
- * After a call to pa_stream_write() the write index will be left at
- * the position right after the last byte of the written data.
- *
- * \section latency_sec Latency
- *
- * A major problem with networked audio is the increased latency caused by
- * the network. To remedy this, Polypaudio supports an advanced system of
- * monitoring the current latency.
- *
- * To get the raw data needed to calculate latencies, call
- * pa_stream_get_timing_info(). This will give you a pa_timing_info
- * structure that contains everything that is known about the server
- * side buffer transport delays and the backend active in the
- * server. (Besides other things it contains the write and read index
- * values mentioned above.)
- *
- * This structure is updated every time a
- * pa_stream_update_timing_info() operation is executed. (i.e. before
- * the first call to this function the timing information structure is
- * not available!) Since it is a lot of work to keep this structure
- * up-to-date manually, Polypaudio can do that automatically for you:
- * if PA_STREAM_AUTO_TIMING_UPDATE is passed when connecting the
- * stream Polypaudio will automatically update the structure every
- * 100ms and every time a function is called that might invalidate the
- * previously known timing data (such as pa_stream_write() or
- * pa_stream_flush()). Please note however, that there always is a
- * short time window when the data in the timing information structure
- * is out-of-date. Polypaudio tries to mark these situations by
- * setting the write_index_corrupt and read_index_corrupt fields
- * accordingly.
- *
- * The raw timing data in the pa_timing_info structure is usually hard
- * to deal with. Therefore a more simplistic interface is available:
- * you can call pa_stream_get_time() or pa_stream_get_latency(). The
- * former will return the current playback time of the hardware since
- * the stream has been started. The latter returns the time a sample
- * that you write now takes to be played by the hardware. These two
- * functions base their calculations on the same data that is returned
- * by pa_stream_get_timing_info(). Hence the same rules for keeping
- * the timing data up-to-date apply here. In case the write or read
- * index is corrupted, these two functions will fail with
- * PA_ERR_NODATA set.
- *
- * Since updating the timing info structure usually requires a full
- * network round trip and some applications monitor the timing very
- * often Polypaudio offers a timing interpolation system. If
- * PA_STREAM_INTERPOLATE_TIMING is passed when connecting the stream,
- * pa_stream_get_time() and pa_stream_get_latency() will try to
- * interpolate the current playback time/latency by estimating the
- * number of samples that have been played back by the hardware since
- * the last regular timing update. It is espcially useful to combine
- * this option with PA_STREAM_AUTO_TIMING_UPDATE, which will enable
- * you to monitor the current playback time/latency very precisely and
- * very frequently without requiring a network round trip every time.
- *
- * \section flow_sec Overflow and underflow
- *
- * Even with the best precautions, buffers will sometime over - or
- * underflow. To handle this gracefully, the application can be
- * notified when this happens. Callbacks are registered using
- * pa_stream_set_overflow_callback() and
- * pa_stream_set_underflow_callback().
- *
- * \section sync_streams Sychronizing Multiple Playback Streams
- *
- * Polypaudio allows applications to fully synchronize multiple
- * playback streams that are connected to the same output device. That
- * means the streams will always be played back sample-by-sample
- * synchronously. If stream operations like pa_stream_cork() are
- * issued on one of the synchronized streams, they are simultaneously
- * issued on the others.
- *
- * To synchronize a stream to another, just pass the "master" stream
- * as last argument to pa_stream_connect_playack(). To make sure that
- * the freshly created stream doesn't start playback right-away, make
- * sure to pass PA_STREAM_START_CORKED and - after all streams have
- * been created - uncork them all with a single call to
- * pa_stream_cork() for the master stream.
- *
- * To make sure that a particular stream doesn't stop to play when a
- * server side buffer underrun happens on it while the other
- * synchronized streams continue playing and hence deviate you need to
- * pass a "prebuf" pa_buffer_attr of 0 when connecting it.
- *
- * \section disc_sec Disconnecting
- *
- * When a stream has served is purpose it must be disconnected with
- * pa_stream_disconnect(). If you only unreference it, then it will live on
- * and eat resources both locally and on the server until you disconnect the
- * context.
- *
- */
-
-/** \file
- * Audio streams for input, output and sample upload */
-
-PA_C_DECL_BEGIN
-
-/** An opaque stream for playback or recording */
-typedef struct pa_stream pa_stream;
-
-/** A generic callback for operation completion */
-typedef void (*pa_stream_success_cb_t) (pa_stream*s, int success, void *userdata);
-
-/** A generic request callback */
-typedef void (*pa_stream_request_cb_t)(pa_stream *p, size_t length, void *userdata);
-
-/** A generic notification callback */
-typedef void (*pa_stream_notify_cb_t)(pa_stream *p, void *userdata);
-
-/** Create a new, unconnected stream with the specified name and sample type */
-pa_stream* pa_stream_new(
- pa_context *c /**< The context to create this stream in */,
- const char *name /**< A name for this stream */,
- const pa_sample_spec *ss /**< The desired sample format */,
- const pa_channel_map *map /**< The desired channel map, or NULL for default */);
-
-/** Decrease the reference counter by one */
-void pa_stream_unref(pa_stream *s);
-
-/** Increase the reference counter by one */
-pa_stream *pa_stream_ref(pa_stream *s);
-
-/** Return the current state of the stream */
-pa_stream_state_t pa_stream_get_state(pa_stream *p);
-
-/** Return the context this stream is attached to */
-pa_context* pa_stream_get_context(pa_stream *p);
-
-/** Return the device (sink input or source output) index this stream is connected to */
-uint32_t pa_stream_get_index(pa_stream *s);
-
-/** Connect the stream to a sink */
-int pa_stream_connect_playback(
- pa_stream *s /**< The stream to connect to a sink */,
- const char *dev /**< Name of the sink to connect to, or NULL for default */ ,
- const pa_buffer_attr *attr /**< Buffering attributes, or NULL for default */,
- pa_stream_flags_t flags /**< Additional flags, or 0 for default */,
- pa_cvolume *volume /**< Initial volume, or NULL for default */,
- pa_stream *sync_stream /**< Synchronize this stream with the specified one, or NULL for a standalone stream*/);
-
-/** Connect the stream to a source */
-int pa_stream_connect_record(
- pa_stream *s /**< The stream to connect to a source */ ,
- const char *dev /**< Name of the source to connect to, or NULL for default */,
- const pa_buffer_attr *attr /**< Buffer attributes, or NULL for default */,
- pa_stream_flags_t flags /**< Additional flags, or 0 for default */);
-
-/** Disconnect a stream from a source/sink */
-int pa_stream_disconnect(pa_stream *s);
-
-/** Write some data to the server (for playback sinks), if free_cb is
- * non-NULL this routine is called when all data has been written out
- * and an internal reference to the specified data is kept, the data
- * is not copied. If NULL, the data is copied into an internal
- * buffer. The client my freely seek around in the output buffer. For
- * most applications passing 0 and PA_SEEK_RELATIVE as arguments for
- * offset and seek should be useful.*/
-int pa_stream_write(
- pa_stream *p /**< The stream to use */,
- const void *data /**< The data to write */,
- size_t length /**< The length of the data to write */,
- pa_free_cb_t free_cb /**< A cleanup routine for the data or NULL to request an internal copy */,
- int64_t offset, /**< Offset for seeking, must be 0 for upload streams */
- pa_seek_mode_t seek /**< Seek mode, must be PA_SEEK_RELATIVE for upload streams */);
-
-/** Read the next fragment from the buffer (for recording).
- * data will point to the actual data and length will contain the size
- * of the data in bytes (which can be less than a complete framgnet).
- * Use pa_stream_drop() to actually remove the data from the
- * buffer. If no data is available will return a NULL pointer \since 0.8 */
-int pa_stream_peek(
- pa_stream *p /**< The stream to use */,
- const void **data /**< Pointer to pointer that will point to data */,
- size_t *length /**< The length of the data read */);
-
-/** Remove the current fragment on record streams. It is invalid to do this without first
- * calling pa_stream_peek(). \since 0.8 */
-int pa_stream_drop(pa_stream *p);
-
-/** Return the nember of bytes that may be written using pa_stream_write() */
-size_t pa_stream_writable_size(pa_stream *p);
-
-/** Return the number of bytes that may be read using pa_stream_read() \since 0.8 */
-size_t pa_stream_readable_size(pa_stream *p);
-
-/** Drain a playback stream. Use this for notification when the buffer is empty */
-pa_operation* pa_stream_drain(pa_stream *s, pa_stream_success_cb_t cb, void *userdata);
-
-/** Request a timing info structure update for a stream. Use
- * pa_stream_get_timing_info() to get access to the raw timing data,
- * or pa_stream_get_time() or pa_stream_get_latency() to get cleaned
- * up values. */
-pa_operation* pa_stream_update_timing_info(pa_stream *p, pa_stream_success_cb_t cb, void *userdata);
-
-/** Set the callback function that is called whenever the state of the stream changes */
-void pa_stream_set_state_callback(pa_stream *s, pa_stream_notify_cb_t cb, void *userdata);
-
-/** Set the callback function that is called when new data may be
- * written to the stream. */
-void pa_stream_set_write_callback(pa_stream *p, pa_stream_request_cb_t cb, void *userdata);
-
-/** Set the callback function that is called when new data is available from the stream.
- * Return the number of bytes read. \since 0.8 */
-void pa_stream_set_read_callback(pa_stream *p, pa_stream_request_cb_t cb, void *userdata);
-
-/** Set the callback function that is called when a buffer overflow happens. (Only for playback streams) \since 0.8 */
-void pa_stream_set_overflow_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata);
-
-/** Set the callback function that is called when a buffer underflow happens. (Only for playback streams) \since 0.8 */
-void pa_stream_set_underflow_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata);
-
-/** Set the callback function that is called whenever a latency information update happens. Useful on PA_STREAM_AUTO_TIMING_UPDATE streams only. (Only for playback streams) \since 0.8.2 */
-void pa_stream_set_latency_update_callback(pa_stream *p, pa_stream_notify_cb_t cb, void *userdata);
-
-/** Pause (or resume) playback of this stream temporarily. Available on both playback and recording streams. \since 0.3 */
-pa_operation* pa_stream_cork(pa_stream *s, int b, pa_stream_success_cb_t cb, void *userdata);
-
-/** Flush the playback buffer of this stream. Most of the time you're
- * better off using the parameter delta of pa_stream_write() instead of this
- * function. Available on both playback and recording streams. \since 0.3 */
-pa_operation* pa_stream_flush(pa_stream *s, pa_stream_success_cb_t cb, void *userdata);
-
-/** Reenable prebuffering as specified in the pa_buffer_attr
- * structure. Available for playback streams only. \since 0.6 */
-pa_operation* pa_stream_prebuf(pa_stream *s, pa_stream_success_cb_t cb, void *userdata);
-
-/** Request immediate start of playback on this stream. This disables
- * prebuffering as specified in the pa_buffer_attr
- * structure, temporarily. Available for playback streams only. \since 0.3 */
-pa_operation* pa_stream_trigger(pa_stream *s, pa_stream_success_cb_t cb, void *userdata);
-
-/** Rename the stream. \since 0.5 */
-pa_operation* pa_stream_set_name(pa_stream *s, const char *name, pa_stream_success_cb_t cb, void *userdata);
-
-/** Return the current playback/recording time. This is based on the
- * data in the timing info structure returned by
- * pa_stream_get_timing_info(). This function will usually only return
- * new data if a timing info update has been recieved. Only if timing
- * interpolation has been requested (PA_STREAM_INTERPOLATE_TIMING)
- * the data from the last timing update is used for an estimation of
- * the current playback/recording time based on the local time that
- * passed since the timing info structure has been acquired. The time
- * value returned by this function is guaranteed to increase
- * monotonically. (that means: the returned value is always greater or
- * equal to the value returned on the last call) This behaviour can
- * be disabled by using PA_STREAM_NOT_MONOTONOUS. This may be
- * desirable to deal better with bad estimations of transport
- * latencies, but may have strange effects if the application is not
- * able to deal with time going 'backwards'. \since 0.6 */
-int pa_stream_get_time(pa_stream *s, pa_usec_t *r_usec);
-
-/** Return the total stream latency. This function is based on
- * pa_stream_get_time(). In case the stream is a monitoring stream the
- * result can be negative, i.e. the captured samples are not yet
- * played. In this case *negative is set to 1. \since 0.6 */
-int pa_stream_get_latency(pa_stream *s, pa_usec_t *r_usec, int *negative);
-
-/** Return the latest raw timing data structure. The returned pointer
- * points to an internal read-only instance of the timing
- * structure. The user should make a copy of this structure if he
- * wants to modify it. An in-place update to this data structure may
- * be requested using pa_stream_update_timing_info(). If no
- * pa_stream_update_timing_info() call was issued before, this
- * function will fail with PA_ERR_NODATA. Please note that the
- * write_index member field (and only this field) is updated on each
- * pa_stream_write() call, not just when a timing update has been
- * recieved. \since 0.8 */
-const pa_timing_info* pa_stream_get_timing_info(pa_stream *s);
-
-/** Return a pointer to the stream's sample specification. \since 0.6 */
-const pa_sample_spec* pa_stream_get_sample_spec(pa_stream *s);
-
-/** Return a pointer to the stream's channel map. \since 0.8 */
-const pa_channel_map* pa_stream_get_channel_map(pa_stream *s);
-
-/** Return the buffer metrics of the stream. Only valid after the
- * stream has been connected successfuly and if the server is at least
- * Polypaudio 0.9. \since 0.9.0 */
-const pa_buffer_attr* pa_stream_get_buffer_attr(pa_stream *s);
-
-PA_C_DECL_END
-
-#endif